CHAPTER XII.
New Zealand—Boiling Fountains and Lakes
In the eruptions of mud volcanoes, described in the foregoing chapter, a frequent ingredient is boiling water. There are, however, several instances in which there are thrown up jets of boiling water that are not intermingled with mud, but in which the water is either pure or impregnated with some mineral which it holds in perfect solution. Of this nature are the Geysers of Iceland and California, already described.
In New Zealand there is another variety of this phenomenon, the boiling water issuing forth, not in intermittent jets, as in the Geysers, but in perpetually flowing springs, forming lakes, in which the water remains nearly at the boiling point. These springs and lakes occur at a place called Roto-Mahana. The annexed woodcut will convey an idea of their appearance.
There are several basins raised one above another, and all higher than the level of the large lake. The highest is of an oval form, and about two hundred and fifty feet in circumference. It is filled from an opening at the height of about a hundred feet above the level of the lower lake. At various stages below this upper basin are numerous other springs, from which several similar basins are filled. The whole of these basins empty themselves into the large lake below, and the water in all of them is nearly boiling hot, giving forth, with a hissing sound, volumes of white vapour.
[Illustration: Boiling Lakes of Roto Mahana]
These waters are richly impregnated with carbonate of lime, which has formed all round the margins of the basins beautiful incrustations of snowy whiteness. The sand round the lake is very warm; and if a stick be thrust into it, jets of steam arise.
Doubtless, some years hence, the enterprising English settlers will establish hot baths here. Not far from the lake there are smaller basins, in which the water is not beyond what would be agreeable for a warm bath; while it is of a blue colour and beautifully clear.
On both banks of the river Waikato, also in this neighbourhood, are found numerous basins full of boiling mud or slime, which cannot be approached save with extreme care, owing to the softness and slipperiness of the soil. The largest of these basins is oval in form, 14 feet long by 8 feet wide, and about as much in depth. It contains hot mud of a bright red colour, being strongly impregnated with oxide of iron. Large viscous bubbles are continually rising to the top, and on bursting they emit a fetid, sulphureous smell. These phenomena are nearly akin to those of a mud volcano.